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国外科学家最近发现,使用强磁场靠近行波管的阴极,能够将噪声降低到过去任何型式的微波电子管所未曾达到过的最低程度.强磁场对行波管起着两大作用,首先,它可以将自阴极发出来的电子通过磁聚焦,成为狭窄微细的电子束,并且使电子束直穿螺线而到达行波管另一端的集电极上.其次,它可以将两种主要噪声源加以抑制:即由散粒效应所产生的噪声和组成电子注的各个电子具有不同的速度所产生的噪声.由于掌握了这一消除噪声的新技术,超低噪声行波管的优良性能将不断得到改进,它的噪声水平将优于参量放大器,它的灵敏度将接近于“脉泽”(受激辐射微波放大器).
Recently, foreign scientists have found that the use of a strong magnetic field close to the cathode of a traveling wave tube can reduce the noise to the lowest level ever achieved by any type of microwave tube. The strong magnetic field plays two major roles in traveling wave tube. Firstly, The electrons emitted from the cathode are focused by the magnetic flux into a narrow and narrow electron beam and the electron beam is passed through the spiral to reach the collector of the other end of the traveling wave tube.Secondly, it suppresses two main noise sources : That is, the noise generated by the scattering effect and the noise produced by the different electrons making up the electron injection have different speed.Because of this new noise-canceling technology, the excellent performance of ultra-low noise TWT will continue to be improved , Its noise level will be better than the parametric amplifier, its sensitivity will be close to “maser ” (stimulated radiation microwave amplifier).